Optical instrument



Nov. 6, 1928.

u 1,6902 70 F. H. cARssow OPTI CAL INSTRUMENT Filed Aug. 16, 1926 4 snelste-sheet 1 INVENTOR- ATTGRNEYS Nov. 6, 192s. 1,690,270

v F. H. cARssow OPTICAL INSTRUMENT Fi'led Aug. 16 4 Sheets-Sheet 2 INVENTOR BYE.

ATroRNEYs.

Nov'. 6, 1928. 1,690,270

" F. H. cARssow l OPTICAL INSTRUMENT Filed Aug. 16. 1926 4 Sheets-Sheet 3 J'fz fr), 1113/ V/ 1" INTER PUPILARY DISTANCE NVENTOR ATTORNEYS' Nov. 6, 1928.

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INVENTOR ATTORNEY S;

Patented Nov.` 6i, 197278. i

v UNITED STATES PATENT oFI-ICE FELIX n. densspwfor VALLEJQQ i cALlIFoRisrra` j V-oiy'rICAL` INSTRUMENT. c

1 This inventionirelates to a geometrical in-` strument` and particularly pertains to range finders of the self-contained base type.

e The objectsof my invention arci-first', to

provide an instrument in which the distance bet-weenthe objective lenses is reduced yto a minimum in order toV diminish the deforming effects producedby unequal temperature distribution in the lens carrier; second, to collect i0 in a `compact mddl-egroup allk the optical parts, except'the optical square at each end of the base, and such optical elements as areV i l merging them into one,-it iseessential thatV the light raystransmitted by them turned Q through 90 degrees by a reflector adjacent to the same,-and directed to a rear Aset .ofrelectors where they are turned through 180 degrees, therefrom `continuing infseparate paths toward the observer. In the monocular instrument, the 4light rays after leaving the rear set of reflectors pass through a systemof eye-'piece prisms to appear at the foca-l plane commonito the objectives and eye-piece,

as complementary partial image fields. In

the binocular instrument',` the Llight rays after leaving the rear set of reflectors arebroughtto ocusas .stereoscopically com'plementarj7 image fields, eachinthe focal plane off its telescopic combination. V- j 4o Broa'dly" considered, the 'instrument in which this inventionis concerned, consists of the optical elementsand their ymountings collected in a compact middle group, embody` ing `the novel features, `ctmubiued with' light passage tubes, to the outer ends of which are attached the base terminating optical squares.

The invention is illustrated, in an exampla-ry way, by the accompanying drawings, in which: j g l 50, Figurel is an enlarged transverse sectional View through a monocular co-incidence in-' strument embodyingthe principles of my intions and displacements due to temperature vention Fig. 2 `is a front elevation looking in the direction of line 2-f2, of Fig."1 showing `the cam used in' Ilocking together and freeing from one another the range dial and the ad j usting ring gear of the instrument shown in Fig. l; Fig. Bis a front elevation lookingin the direction of line`3-3 of Fig. l illustrating parts ofthe range dial and adjusting ring gear of the inst-rumentshown inFig. 1;Fig. 4. is a partial view of a longitudinal section along line 4 4 of Fig. l and shows the objecti've lenses andthe adjacent or objective re-V flectors i-n their carrier,` and the measuring and adjusting prisms; Fig. 5 isa horizontal! section along `line 5-5 of Fig.` 1; Fig. 6 is a p art-iai view "of a vertical sectionthroughthe instrumentalong` line -6-`6of F ig.` `l and shows thegears and shafts used in moving the measuring and adjusting prisms; Fig. 7 is ahorizontal central section, looking down, Wardly showing diagrammatically the ar rangement ofthe optical parts ofthe middle group illustrated in detail in Figs. l to 6 inelusive,y and their relationship to the optical squares for the monocular co-incidence instrument; Fig. 8 is a horizontal central secs tion looking downwardly, `showing diagrammaticalfly an instrument similar to that shown in Fig. 7, but modilied to apply toa binocular stereoscopic range finder; Fig. Saisadiagrammatic view illustrating the adjustability of the inter-pupillary distance for the eye-pieces ina binocular type ot' range finder; Fig. 9 is vertical section along line v9 '.9 of'Fig. l1, `and showsj diagrammatically`y the arrange ment of the optical parts ofthe middle group for an instrument in which the rear set of yreflect-ors consists of vtwo reiiecting surfaces whoseintersectionlies in a plane substantially normal to the longitudinal axis of the optical base; Fig. l() isa vertical section along line 10*10 of Fig. l2, and shows diagrammaticallv the arrangement of the optical parts of the middle group for an instru` `ment in which therear set of reilectorscon-l sists of two reflecting surfaces whose intersection is substantially parallel tothe longi tudinal axis of the optical base; and Figs. `ll' and 12 are horizontal sections along the lines 1l-,ll and l2 l2 of Figs. 9 and lllrespecand their relationship to the opt-ical squares.

Similar letters and numbers refer to similar parts throughout the several views.

Referring to the drawings in detail, the outer casing of the middle group consists ol parts l and 2, detachably fastened together. Part l is connected at the light passageways 3, with the light passage tubes 50 and 51, and through them with the optical squares 52 and Held in place within this casing by the bosses and sockets a and the screw point and socket 5, are the inner casing parts (i and 7, also detachably fastened together. lliithin this inner casing are mounted, the carrier 8, with the objectives i), and their adjacent or objective reflectors 10; the carrier ll, with the rear set of reflectors 12; the measuring and halving prism screws and pinions i3 and il, on which travel the cells contain- `.ng the measuring and halving prisms l5 and lo; the spring cases 17, with springs and plugs for holding 13 and ll in their true positions; and the measuring and halving prism guides i8. The carrier 8 with its segments of spherical surfaces 19, bears on the cylindrical surfaces of G without transmitted strains and is held by the heads of the screws 20, bearing against the sides of the cylindrical hole 2l. and the oblong hole The carrier il is held in place without the introduction of exterior distorting strains to itself, by the screw and the elastic washer 2st and the spherical points of the screws resting in the neat fitting holes 2G. To the front of the inner casing is attached a cell containing the eye-piece prisms QT, 28, 25) and 30. On the top of the inner casing is mounted a rotatable shaft with the gear 3l meshing with the pinion ol 1i. One end of this shaft is formed to receive a key by which it is turned when making halving adjustments.

On the top `of the outer easing is mounted the. adjusting ring gear S2 meshing with the pinion of the measuring prism screw 13 and is supported b v the hearing' 323 and enclosed b v the case parts 34;, 3? and 3o. 'lfhrough the tubular part of 32 passes the stem of the range dial 3T, and the)Y are held to rotate as one bv the springs and bolts 23S. and the fixed and sliding spring seats` 39 and l0, when the cam and cam plate Lil are in the position shown. lVhcn the cam is turned from the position here shown it lifts el() from pressure contact with 32, and permits relative rotation between the range dial 3T and the adjusting ring gear 32. In order to rotate graduallvv or hold itfixed.y a clamp ringstil, encircling a. cylindrical part otl 32 ma); be locked to the same by the clamp screw lil. Rotary motion may then be communicated to the adjusting ring gear by the tangent screw 4&1-, and the opposing spring and plug in the spring ease lo carried b v the standards attaehed to the Aase part Set. An indes line 4G on 35 shows the angular position of the adjusting ring gear when testing the infinite distance readings. The plate 47 nieves up and down along guide rods, and carries a projection i8 which fits in the spiral groove on the face of the range dial. so that its pointer always remains at the edge of the range scale, and indicates the range. il positive eyepiece 49 is mounted on the Afront part of the outer casing and is capable of being moved along its axis for purposes ol focussing.

The eye-piece prism system here shown consists of two pairs of like triangular prisms. Each prism is shown with its h vpothenuse surface perpendicular to its bases or ends, and its light transmittingr surfaces making equal angles, one with the base and one with the top of the prism. Together they act on the transmitted light rays like the parallel sides of a glass plate. B v arranging these prisms in pairs, a ray of lightin passing through them emerges undivided as well as parallel to its incident direction. The two prisms directly in front of the eye-piece have their lijvpothenuse surfaces crossed and the lines formed b v the intersection of their contact and emergent surfaces are superposed to form the selliarating line lying in the focal plane of the objectives and eye-piece. The emergent. surfaces slope from the separating line, tova rd the, eye-piece, rendering the contact surfaces invisible. when viewed through the eye-piece, and the separating.r line is seen as a sharp line between the upper and lower half image fields. The images formed under the condition shown in the drawings are inverted though normal as to right and left. To make the images normal as to the vertical direction, or re-invert them, the hypothenuse surfaces of 2T and 3() or 28 and 29, or one of the cathctus surfaces of each of the rear prisms l2, should be ground as a roof angle. In the steroscopie instrument here digrammatically illustrated. the eye-piece prisms are omitted, and in order to make the imagrs vertically normal one of the cathetus surfaces of each prism l2, should be ground to a roof angle.

Variations of the optical arrangements shown in the accompanying drawings can be made by shifting the objective lenses from the positions shown to positions between the objective reflectors and the rear set of reflectors. Other variations can be made especially when the above inter-change of positions of the ob jectivcs and objective reflectors is made to optical combinations like that shown in Figs. 1l and 1Q, wherein the two olriectives can be replaced by one centrally located lens, and the light rays n'loving from the rear .vet of reflectors to the eye-piece or eye-pieces can be directed in separate paths. as a pair either over the top or below the bottom or around one or the other side of the objective reo Hector, or one over the top and the other be-` 1Ull llll

of Ebb objective mflector.

20 `two sepainte eyeflpieces 49a and`4l9b. `As rep#4 ,in Fig@Y `i malin-afstaan@ pticaipatii throiiglthe..Y monocular eo-incidence instru:Y ment here thevliight rays arerepresented as entering `the opticalsquares 52 and 53V and i `being.reflected therefromthrough light-pastuhesand 51 of the light passagevvays 3. Theilighti asses through the objectives F9 andtbieir a jacent or objective reflectors 1() totheset of rear'refleotors 121 and thence through the measuring vand halving prisms lniid ltol'the eyespiece prisms 27, 28, 29

and El) Where thev light is focussed 'in the eyepiece 49. f

4In `Fig'.4 "S l have show-n the principle of Y my invention as applied toa binocular stereoscolcxie range finder kand the passage of the lightfnaystothe separate. field lenses. in the resented in both igs. 7 und 8 the measuring and halving prisms 15 and 1G are adjustable. in position; The measuring land halving prism 15V may occupy for example the dotted line position 15 under control of the tangent screw 44. As represented in Fig. 8a the binocularinmrunientsmay `have the eyepieces 49* and 49h laterally adjustable for'conti'olling` the interpupillary distance. The lens 4"carriers for the yeye-pieces 49 and 491 may be pivotallymounted at 6() and '61 allowing the.

lenses to adjnstedifor the convenience of ditlenentobservers; i j

In Fig. 9 I have shown diagranimatically -thearrangement of optical parts torthe middle group of a rangeifinder Twherethe separate remi' fset of reflectors 12 described in connection with Figs. 1 to l8 are replaced by asin glo rea-r reflector"1-2oonsistingof two reflect ling surfaces illustrated more clearly in Fig 11 whose 4lister-section lies-in a plane sub- "to the lmigitudinal axisof the optical base.

In this construction the rear reflectorv 'comprises a single reflecting body 12b .as illustratedmoreclearly in Fig. 12. The reflector 12h hastivo reflecting surfaces Whose intere section is substantially parallel tothe longitudinal .axis of the optical base and serve to cooperate with thoobjective reflectors 10.

The passage of lightthrough the range finder in the cases Where the rear reflector is formed lbyv asinglle newtor Vwill be more clearly understood toy-considering Figs. 9iand lland 10and `12 jointly inasmuch asthe light rays pass/inthe same vertical planeinjthebari--l zontal sections of Figs. l1 and 12-and can only be seen in the vertical sections kot Figs. 9 and l0 in proper arrangement. 1 i f f I have described preferred Aembodiments of my invention in a ia'nge iinder'but I desire .i that 1t be understood that moditicationsmay v be made and that no 4limitations upon the inT vention are intended j other than those im posed by the scopeof the appended claims.

What VI claim" as new and desire tosecure byvLetters Patent'of the UnitedStates son:

1. A range finder comprising in ,coinbinaf4k follows tion a casing havinglight passage tubes ex! y tending in opposite directionstherefrom,a

central inner casing mounted insaid first"` mentioned casing, said centrall inner casing being arranged to receive a removable carrier at each end tliereot, reflectors mounted mounted adjacent the reflectors inthe end of said carrier adjacent said lightpassage tubes, optical means forreceiving light rays and directing said rays through said objec-` tive lenses y:onto the reflectors adjacent thereto where they are directed toward said refy flectors at the `opposite end of said carrier.

measuring and halving prismsV interposed;

in the pathaoflight reflected by said lia-st flcctors vand an ocular' system @for :observing x the images of a distant object.

`in each o said carriers, objective lenses.;

mentioned` reilectors and `eachv'independently Y adjustable in position Wit-lirespect to saidre` 2. A range finder comprisingin combina- 'tion an outer casing having awpairof light' passage tubes extendingin opposite dire tions, optical means in cachot said tubes for receiving `and reflecting light raysy from .a

distant object, a casing .oentrallyinountedz Within. said first mentioned casing and pros,`

vided With a detachable :carrier at `each end thereof, i'electorsymounted in each Kof said carriers, objectivelenses mounted adjacent;-

directing of the saine upon `said reflectors-iat the oppositeend of `.said casing, an image observing system mounted l:on the partspf said casings which lieadjacent .Said light.

image observing system', and a pair of meas` uring and halving prisms-interposed in the the reflectors in the carrier-adjacent said llight passage tubes for transmitting lighty -i'rom said Vopticaljineans and aiding in thepassage tubes, prisms. forming partof ysaid path of said lfirst mentioned prisms and light Y rays received from said last mentioned Yreflectors, and means: A`for Vlongitudinelly adjusting said measuring and halving tprisms vvithrespect to said first mentioned prisms;v

whereby the. images of an object may .be

moved lrelative to each other While beingY viewedthrough said image observingsystem. v

3. A range finder comprising in,combinaj` tion a casing having a pair of oppositely extending light passage tubes, optical means in each of said tubes for receiving and reflecting light rays, a central casing carried Within said first mentioned Casing and having an independent removable carrier at each end thereof, reflecting surfaces mounted Within each of said carriers, objective lenses positioned adjacent the rcfiecting surfaces in the carrier inmiediately adjacent said light passage tubes, a pair of measuring aud halving prisms adjustable longitudiiially within said central casing from the exterior of said first mentioned casing, an image observing system mounted on said central and outer casings for substantial abutment one with respect to the other and aligned With said measuring and halving prisms and with the reflecting surfaces opposite said last mentioned reflecting surfaces for observing a distant object.

4. A range finder comprising in combination a. casing having a pair of oppositely ex tending light passage tubes, optical means for reflecting light rays through said tubes, a separate casing mounted centrally Within said first mentioned casing and carrying a detachable optical system for cooperating with said optical means, said optical system comprising sets of reflectors at opposite ends of said separate casing, adjustable measuring and halving prisms located between said reflectors, eye-piece prisms positioned adjacent the end of said separate casing and aligned with said measuring and halving prisms, and an image observing system adjacent said eye-piece prisms in said first mentioned casing for observing a distant object.

5. A range finder comprising in combination a casing having a pair of oppositely extending light passage tubes, optical means in said tubes for reflecting light rays, a separate casing centrally positioned in said first mentioned casing, a detachable carrier mounted in each end of said separate casing and extending laterally thereof, each of said carriers having reflecting surfaces mounted therein and the carrier adjacent said light passage tubes having objective lenses therein for receiving light rays from said optical means in said tubes, measuring and halving prisms mounted Within said separate casing and adjustable longitudinally therein by means exterior of said casing, a set of eyepiece prisms mounted in said separate casing and aligned with said measuring and halving prisms; whereby light received from said optical means is passed through said objective lenses and directed at substantially degrees by the reflectors at one end of said separate casing to the reflectors at the opposite end of said separate casing and returned by the last mentioned reflectors to said eye-piece prisms.

G. A range finder comprising in combination a casing, light passage tubes formed by said casing, an inner central casing having its Walls spaced from the walls of said first mentioned casing, a carrier positioned in each end of said second mentioned casing, one of said carriers being laterally cletiiclizflile from said second mentioned casing, and the other carrier being longitudinally removable from said second mentioned casing, reflecting surfaces mounted in said carriers, eyepiece prisms carried by one end of said second mentioned casing and aligned with the reflecting surfaces in one of said carriers, the reflecting surfaces in the other of said carriers being arranged to receive and direct light from said light passage tubes to the refiecting surfaces in said other carrier, said second mentioned carrier having segmentary portions of spherical surfaces located at opposite ends thereof and bearing upon the inner walls of said second mentioned casing.

7. A range finder comprising in combination a casing having light passage tubes eX- tending in opposite directions therefrom, an independent casing centrally mounted Within said first mentioned casing and having its walls spaced from the walls of said first mentioned casing, carriers laterally positioned in opposite ends of said independent casing and positively spaced from the Walls thereof, said carriers being removable from said independent casing at right angles to each other, each of said carriers having optical elements mounted therein with the rcflecting surfaces in one of said carriers aligned with said light passage tubes for directing light to the reflecting surfaces in the other of said carriers, eye-piece prisms centrally positioned in said independent casing in the end adjacent said light passage tubes and aligned with the reflecting surfaces in the opposite end of said independent casiiw.

8. A range finder comprising in combination a casing having light passage tubes extending in opposite directions therefrom, an imlependent casing centrally positioned in said first mentioned casing and spaced from the Walls thereof, carriers positioned in opposite ends of said independent casing and detatchable by movement in directions at right angles one to the other, light reflecting surfaces mounted in said carriers, one of said carriers having segmentary spherical sur faces on opposite ends thereof for engaging the inner surfaces of said independent casing` and means pa.` ig through said independent casing and engaging said segmentary spherical surfaces for securing said carrier in position.

9. A range finder comprising in combination a casing having a pair of oppositely extending light passage tubes, an independent casing mounted centrally within said first mentioned casing, a reflector positioned in apposite ,i ends if :smidindependent ,feasing,

for. simultaneously mounting or C of said eyepiece prisms adjacent one side :fdenrolnting said` reflectors, folegeetire lenses i. `,aligned with "the reflector `ione end of said, independent easing adjacent sai-d light passage tubes,1. means for simultaneously mountingioxd'eiuomting said objective lenses, thereflector in the opposite end of said independent casing `having two reflecting surfaces Whose inter-section is Vsubstantially parallel to the longitudinal axis of said independent casing, a set of eye-piece prisms located centrally` inthe end of said independent piece prisms centrally positioned in one end of said independent casing, a pair of parallel longitudinally extending screws Within said independent casing and alignedwith the axis of said independent casing, a pair of'parallel extending guides` positioned adjacent the `op-V posite side of said independent casing, meas uring and halving prisms arranged to be ad# vanced or retracted by said screws along said guides, and means exterior of said first mentioned vcasing and geared to drive both yof said screws for adjusting the position of said measuring and lialving prisms along said guides by rotatablydriving said screws.

11. A range finder comprising in combination a casing, a" pair of light` passage tubes extending in opposite directions from said casing, an independent casing centrally mounted Within said first mentioned casing, reflecting surfaces mounted in opposite ends of said independentcasing, a set of eye-piece prisms mounted in one end of said independ-v ent casing, measuring and halving prisms aligned betweensaid eyepiece prisms and one set of said reflecting surfaces, a 'pairf of screws located adjacent the top of said inde-l pendent casing and rotatable means mounted on the exterior of said first mentioned casing for imparting rotative movement `tosaid screws and adjusting the position of said measuring and halving prisms with respect to saidy reflecting surfacesry i .12. A range finder comprising` in combina# Y y tion a casing, a pair of light passage tubes eX- tending in opposite directions from said casing, an independent casing mounted centrally within said first mentioned casing, reflecting surfaces carried in opposite ends of said inexterior of said first mentioned casingfor dependent casing, Sa set of Aeyepiece prisms mounted centrally within :one fend :of said independent casing and aligned with" .said re'- flecting surfaces, indepeircleirt ineasuringzandf c hailving prisms longitudinally i* adustnbllem within said independent .casing :and rotatable means exterior v,oiesaid :first mentioned casing for simultaneously selecting the position of said independent measuring and halving prisms with respect to said reflectingsurfaces, and means for locking said measuring and halving prisms in a selected position.

13. A range finder comprising-in combination a casing, a pair of light passage tubes extendingin opposite directions from said casing, an independent casing mounted centrally Within said first mentioned casing, reflecting surfaces carried in opposite ends of said independent casing, a set of eye-piece prisms mounted centrally Within one end of said independent casing and aligned With said reflecting surfaces, independent measuring prisms longitudinally adjustable Within said independent casing and rotatable means simultaneously selecting the position of said independent measuring prisms With respect to said Yreflecting surfaces, and -a springpressed friction clutch. secured to said rotatable means for locking said measuring prisms in a selected position With respect to said eyepiece prisms between said reflecting surfaces.

14. A range finder comprising in combina-` tion a casing, a pair of light passage tubes extending in opposite direc-tions from said casing, an independent casing mounted centrally Within said first mentioned casing, ref'Y fleeting surfaces in opposite ends of said independent casing for receiving and directing light from said light passage tubes, and a .105 system of eye-piece prisms centrallymounted in the end of said independentcasing ad]a' -centsaid light passage tubes, said .eye-piece prisms being constituted by two pairs of like triangular prisms, each prism having Vits hypothenuse surface perpendicular to its basesaiid its light transmitting surfaces dis-` posed a-t equal angles with respect to cach other and a sight carried said firsti'nentioned casing and aligned with said triangular lprisms in said independent casing, Whereby a ray of light in passing through Y the prisms emergesundivided as Well as parallel to its incident directions.

y 15. A range finder comprising in combination a casing, a pair of light passagetubes extending in opposite directions from said casing,l an independent casing mounted centrally Within said first mentioned casing, refleeting surfaces in opposite ends of said 1n- 125 dependent'casing for receiving and directing light from said light passage tubes, theV reflecting surfaces in the endof said inde pendent'casing remote from said light .pas sage tubes having their inter-section in a plane substantially normal to the longitudia system of eye-piece prisms arranged in the nal axis of said casing, a pair of measuring end of said independent casing adjacent said and halving prisms adjustahly positioned in light passage tubes for receiving light rays 1 alignment with said reflecting surfaces, a rofrom said last mentioned reflecting surfaces.

5 tary control member for selecting the posi- In testimony whereof I affix my signature.

tion of said prisms, a spring clutch Jfor fixing said prisms in the positions thus selected, and FELIX H. CARSSOV. 

